[sdiy] Pitch shifter??

[Tony Allgood]

> When you inhale helium, your voice shifts up... so
>
> Essay Question: What did the boy scientists go wrong in their thinking
???

The voice box and throat form a resonant cavity whose natural frequency
is dependant on its size and thus the wavelength of standing waves
produced under excitation. Sound travels faster in helium but as the
wavelength is unchanged, the resulting frequency heard is higher.

You can also show the effect with pipes too.

But its no good in non resonant situation such as a loudspeaker and a
mic.

Interesting DIY experiment. Get a big round balloon and fill it up with
CO2. You now have a primitive sound lens. The CO2 acts to slow sound
waves. Works astoundly well. You can hear things from across crowded
rooms... and shout at people and they can't work out where its coming
from. Great fun.

Regards,

Tony Allgood, Penrith, Cumbria, England

Oakley Modular Synth and TB3030:
www.oakleysound.com/projects.htm
My music: www.mp3.com/taklamakan